Animal anesthesia machine

ABSTRACT

A central molded canister contains a centrally positioned charge of carbon dioxide absorbent. Located beneath the absorbent is a chamber having an outlet and two inlets and a further passageway connected to a rebreathing bag. A source of oxygen connects through a valve assembly to each of the inlets by two separate lines. One of these lines contains a first vaporizer. Leading from the outlet is a line which connects with a breathing tube and then returns to an inlet in the cannister above the carbon dioxide absorbent. A second vaporizer is connected to this line between the chamber outlet and the breathing tube. The second vaporizer comprises an inlet and an outlet communicating with a chamber. Two apertures are also located in the chamber. A jar is attached to the chamber and contains anesthetic liquid. A wick divides the jar into two sections, each communicating with one of the apertures. A vane is pivotally mounted in the chamber and is pivotal between a first position wherein the inlet and outlet communicate directly through the chamber, and a second position wherein the inlet communicates with one of the apertures, through the first section of the jar, through the wick, through the other aperture and then to the outlet.

United States Patent [1 1 Johnson 1 Feb. 26, 1974 [73] Assignee: SnyderManufacturing Company, Inc., New Philadelphia, Ohio 22 Filed: .lune29,1970 211 Appl.No.:50,850

Related US. Application Data [63] Continuation of Ser. No. 685,755, Nov.27, 1967,

[75] Inventor:

abandoned.

[52] US. Cl. 128/188 [51] Int. Cl A6lm 17/00 [58] Field of Search128/188, 191, 172.1

[56] References Cited UNITED STATES PATENTS 2,407,221 9/1946 Bloomheart128/188 2,837,413 6/1958 Hay 128/191 R X 2 868,198 l/1959 Brooke 128/1882,870,764 l/l959 Carlson et al.... 128/188 3,088,810 5/1963 Hay 128/191RX 3,172,405 3/1965 Sugg 128/188 3,192,924 7/1965 Edmondson et a1.128/188 3,240,567 3/1966 Caparreli et a1. 23/284 FOREIGN PATENTS ORAPPLICATIONS 1,375,946 1964 France 128/l72.1

519,203 1940 Great Britain 128/188 630,481 1949 Great Britain 128/188144,260 1957 U.S.S.R.

Primary ExaminerRichard C. Pinkham Assistant ExaminerPaul E. ShapiroAttorney, Agent, or FirmOlson, Trexler, Wolters and Bushnell [57] ABSACTA central molded canister contains a centrally positioned charge ofcarbon dioxide absorbent. Located beneath the absorbent is a chamberhaving an outlet and two inlets and a further passageway connected to arebreathing bag. A source of oxygen connects through a valve assembly toeach of the inlets by two separate lines. One of these lines contains afirst vaporizer. Leading from the outlet is a line which connects with abreathing tube and then returns to an inlet in the cannister above thecarbon dioxide absorbent. A second vaporizer is connected to this linebetween the chamber outlet and the breathing tube. The second vaporizercomprises an inlet and an outlet communicating with a chamber. Twoapertures are also located in the chamber. A jar is attached to thechamber and contains anesthetic liquid. A wick divides the jar into twosections, each communicating with one of the apertures. A vane ispivotally mounted in the chamber and is pivotal between a first positionwherein the inlet and outlet communicate directly through the chamber,and a second position wherein the inlet communicates with one of theapertures, through the first section of the jar, through the wick,through the other aperture and then to the outlet.

2 Claims, 5 Drawing Figures ANIMAL ANESTIIESIA MACHINE REFERENCE TORELATED APPLICATION:

This application is a continuation of U.S. application Ser. No. 685,755,filed Nov. 27, 1967 now abandoned and entitled Animal AnesthesiaMachine.

It is a general object of this invention to provide new and improvedapparatus for administering anesthesia to animals.

It is a more specific object of this invention to provide an anesthesiamachine especially suited for large animals, which is light weight,compact and easily transported.

It is a further object to provide an anesthesia machine of theabove-described type which can be easily assembled and disassembled forpurposes of cleaning, drying and transporting.

It is still another object of this invention to provide an anesthesiamachine which is of the closed circuit type and which, due to aone-piece canister portion, is leakproof and is therefore also usablefor manual artificial respiration, and is virtually indestructible.

Other objects and advantages of the present invention will becomeapparent from the following description and the accompanying drawingswherein:

FIG. 1 is an exploded perspective view of an anesthesia machineaccording to the invention;

FIG. 2 is a schematic representation of the circuit of the machine ofFIG. I;

FIG. 3 is a cross-sectional view of the in-the-circuit vaporizer unitshown in FIG. 1, taken along the line 33 thereof;

FIG. 4 is a cross-sectional view of the in-the-circuit vaporizing unitof FIG. 3, taken along the line 4-4 thereof; and

FIG. 5 is a cross-sectional view of the in-the-circuit vaporizing unitof FIG. 4 taken along the line 5-5 thereof.

Referring now to the drawings in more detail, FIG. 1 shows a preferredembodiment of an animal anesthesia machine according to the invention.The machine includes a canister or housing 12, shown here having a shapesimilar to that of a large milk can, which is preferably of one-piecetranslucent plastic molded construction. The milk can shape of thecanister with its wide base portion 14, serves to stabilize the canisterso that it will be prevented from being upset during the anesthetizingprocess. The base portion 14 defines a mixing chamber and includes onopposite sides thereof a pair of apertures or openings 16 and 18, eachof which are surrounded by a respective protruding neck portion 22 and24 for receiving in a slidable, force fitting, slip-together fashion,one end 25 of a hose 26 and the connector portion 27 of a reservoir bag28, respectively. The main body portion 32 of the canister 12 iscylindrically shaped and has integrally molded therewith near the topthereof a pair of handle portions 34 which, along with casters 35attached to base 14, provide a means by which the canister 12 may beeasily transported. Near the top of the cylindrically shaped main bodyportion 32 is a third aperture 36, also having a protruding neck portion38 integrally molded therewith, and provided to receive one end 97 of ahose 42, also in an overlapping slip-together, relationship therewith.Directly in the top of body portion 32 is a large opening 44 throughwhich carbon dioxide absorbing material 52, such as soda lime crystalsor the like, may be placed into the canister. This material can best beseen in FIG. 2 of the drawings. A resilient O-ring 46, preferably ofrubber or the like material, is provided to seal aperture 44 upon thefitting of lid 48 onto the latter. The relation of O-ring 46 and lid 48to the main body 32 of canister I2 is best shown in FIG. 2 of thedrawings where it can be seen that O-ring 46 is placed around lid 48 atindented portion 47 thereof. As the lid is placed onto the canister, theradially extending O- ring is force fitted into the opening 44 so as togrip, radially outwardly, against the inner walls 49 of aperture 44. Toprevent the soda lime 52 from falling into the base portion I4 there isprovided a conical shaped,.

stainless steel screen 54 extending upwardly into the material, andhaving openings therein which are small enough to contain the absorbentmaterial and yet allow the circulation of gases therethrough.

An indentation 56 has been integrally molded into base portion 14 ofcanister 12 to receive a vaporizer unit 58 containing the anesthetic, inthis case, halothane, used in the anesthetizing process. As can be seen,the vaporizer 58 is connected by means of a tube 62 to a flow meter 64which in turn is connected by a tube 66 to an oxygen tank or supplysource 68. The flow of oxygen from the source 68 is controlled in a wellknown manner by an oxygen regulator 72 located at the outlet of oxygensource 68. A flood valve '74 is provided near the inlet to flow meter 64so that oxygen from source 68 may be channeled either through flow meter64, into the vaporizing unit 58, or through a tube 76 directly into thebottom or base portion 14 which provides a mixing chamber or area forcanister 12, and in turn to reservoir bag 28 which is shown supported atground level adjacent the canister I2. The manipulation of the oxygenflow valve 74 will be explained below in greater detail. The outlet ofvaporizer 58 is connected through a tube 78 which transfers anestheticgas into base portion 14 of canister 12.

The anesthesia machine according to the invention may also be used-withan in-the-circuit vaporizing unit 59, shown adjacent hose 26 in FIG. Iof the drawings, if a methoxyfluorane anesthetic is desired to be used,the unit 59, which will be described in greater detail below, includes apair of coupling members 226 and 221 which, when using the unit 59, areconnected to respective sections 117 and 19 of hose 26. Vaporizer units58 and 59 are for separate use; thus, if when unit 59 is used, theoxygen flow from valve 74 will be diverted from vaporizer unit 58 so asto remove the lastmentioned vaporizer from the circuit, and whenvaporizer unit 58 is used, unit 59 will not be connected to hose 26.

A Y-shaped bi-directional valve assembly 82 including three apertures84, 86 and 88, respectively, two of which, 84 and 86, have protrudingneck portions 92 and 94, respectively, similar to those on canister 12described above, has been provided to receive in sliptogetherrelationship at the aforementioned neck portions thereof, the ends 96and 98 of hoses 26 and 42, respectively. The third opening or aperture88 in valve assembly 62 has fitted thereto a slip-on coupling 102 forattachment thereof to an endotracheal tube adapter 104 connected to anend 105 of an endotracheal tube 106. The endotracheal tube, as is knownin the art, is provided to be received by the animal undergoing theanesthetic process. An inflatable endotracheal tube cuff 108 is providedat the other end 107 of the endotracheal tube 106 for placement into thetrachea of the animal so that the tube 106 will not become dislodgetherefrom during the administering of anesthesia. Connected toendotracheal tube 106 is a second tube 112 which has attached thereto anendotracheal indicator balloon 114 used to detect the receipt ofanesthesia by the animal being anesthetized. Valve assembly 82 alsoincludes at the upper end thereof and exhaust valve 116 which serves toeliminate a portion of the carbon dioxide being exhaled through the tube106 by the animal undergoing anesthesia.

Referring now to FIGS. 3 through 5 of the drawings, wherein there isillustrated the in-the-circuit vaporizer unit 59, mentioned above. Thevaporizer unit comprises a cylindrically shaped jar 216 partially filledwith liquid anesthetic 215 of the methoxyfluorane type. The jar 216 isattached to the circular head portion 290 of the unit; in this case thejar 216 includes threads 291 at the neck 292 thereof which mate withthreads 293 of head portion 290. A force fitted interconnection or othermeans may also be used to hold jar 216 to the head portion 290 ifdesired. A wick 212 extending downwardly into the anesthetic liquid 215is attached to a circular plate 218 located in head portion 290 andresting on shoulder portion 294 thereof. The wick divides the jar 216into sections 213 and 214. The plate 218 has located therein a pair ofapertures 211 and 217, one of which communicates with section 213 of jar216 and one of which communicates with section 214, respectively. A vane229 is rotatably mounted on a spindle 299 in compartment 295 above plate218 in head portion 290. Extending outwardly from compartment 295 is thefree end 296 of spindle 299 which has connected thereto an indicator bar230 provided for manually setting the vane 229 to provide eitheranesthesia or pure oxygen to the animal being anesthetized. The vane, aswill be noted, is narrow on one end, 298 thereof and broad andtriangularly shaped at the other end 297 thereof. As mentioned above, apair of coupling members 220 and 221 are provided on either end of thecompartment 295 and are joined by channel 228 which is an integral partof compartment 295. The coupling members are used to interconnect thevaporizing unit 59 with hose 26 into the circuit of the anesthesiaapparatus.

As can be seen in FIG. 3 of the drawings, through the manipulation ofindicator bar 230, vane 229 can be moved to the position as shown insolid lines wherein the aperture 217 is sealed or covered by the wide,triangularly shaped end 297 of the vane and wherein the narrow,needle-like end 298 blocks entry into aperture 211, so that only oxygencoming from the left section of hose 26, as shown in FIG. 3, passesdirectly through channel 228. The vane 229 is also positionable as shownin dotted lines wherein the narrow end 298 of the vane blocks channel228 but opens both apertures 211 and 217. In this position anestheticgas is channeled to the animal undergoing anesthesia.

For purposes of affording a more complete understanding of theinvention, it is advantageous now to describe in greater detail the useof the above-described anesthesia machine in the anesthetizing process.

To begin with, canister 12, being held by integrally molded handles 34may be rolled on casters 35 to the location where it is to be used.Because of the light weight of the canister, due to its molded plasticconstruction, it is also easily carried when it is not practical to berolled from place to place and is virtually indestructible if dropped orbumped in the moving process. Once situated, lid 48 is removed from thecanister and the soda lime material 52 within the canister is checked tosee that it still is in an active state. This will be apparent from thetop one or two inches of the soda lime crystals which, if darkened,require replacement or reactivation. Because the canister is molded of atranslucent plastic material, detection of the darkened soda lime duringthe process is possible without need for removal of lid 48. After thecrystals have been checked the remaining components of the machine,which can be transported in a compact package along with the canister,are assembled thereto. Ends 25 and 97 of hoses 26 and 42, respectively,are slipped over neck portions 22 and 38, respectively, and theconnector 27 of reservoir bag 28 is fitted over neck portion 24 ofaperture 18 in base 14 of the canister. The opposite ends 96 and 98 ofhoses 26 and 42, respectively, are then connected to neck portions 94and 92, respectively, of Y-valve assembly 82 in a like manner. TheY-valve assembly is in turn connected at aperture 88 to the endotrachealtube 106 by means of fittings 102 and 104, respectively. After theconnections have been made, oxygen supply 68 is attached to flow valve64 by means of hose 66. At this point, the exhaust valve 116 of Y-valveassembly 82 is closed and the oxygen tank or source 68 is opened to fillthe reservoir bag 28. Leaks are checked for by firmly pressing on thebag as it is being tilled, after which vaporizer jar 58, which hasalready been placed into position in indentation 56 provided in the baseportion of the canister, is filled with a suitable anesthetic, such asliquid halothane. To fill jar 58, lid 57 thereof is removed and theliquid anesthetic is poured thereinto. After filling the vaporizer jar,exhaust valve 116 of Y-valve assembly 82 is opened an is kept openduring the remainder of the process. This is important for gooddenitrogenation and prevention of hypoxia; i.e., reduction of oxygentension and/or decrease in oxygen volume percentage, for as the animalexhales, a portion of the carbon dioxide and excess nitrogen beingexpelled by the lungs is eliminated through valve 116, thus preventingtoo great an amount of nitrogen from being recirculated to andaccumulated in the blood stream of the animal.

Once the animal has been restrained, in preparation for receipt of theanesthetic gas, a dental wedge is inserted between the upper and lowercheek teeth of the animal. The animals tongue is withdrawn and thecuffed end 108 of the endotracheal tube 106 is inserted into the pharynxthereof. As the animal inspires, the tube 106 is pushed gently into thetrachea and the cuff portion 108 inflated to insure the implantation ofthe tube therein. At this time, the valve 74 should be positioned tobubble oxygen from source 68 through the liquid anesthetic in vaporizer58 (see FIG. 2). The vaporized anesthetic then passes through tube 78into base portion 14 filling the latter. As the animal inhales a mixtureof oxygen and anesthetic gas from within base 14, and additional oxygenfrom reservoir bag 28, is drawn through hose 26 and one-way valve 122 inbidirectional Y-valve assembly 82, and in turn through endotracheal tube106 into the lungs of the animal (not shown). No anesthetic gas mixturecan enter hose 42 through valve 124 in Y-valve assembly 82, for theforce created by the inhalation of the animal acts to close valve 124thereof.

Upon exhaling, the carbon dioxide and other waste gases expelled fromthe lungs of the animal pass in a reverse direction through endotrachealtube 106 into Y- valve assembly 82. At this point a portion of the gasesare eliminated from the otherwise closed system through exhaust valve116 which remains open throughout the process. The remainder of thewaste gases pass, through one-way valve 124, into the aperture 36 in theupper portion of canister 12. None of the gases can enter valve 122 for,due to the exhalation, the valve is forced to a closed position. Duringexhalation, a portion of the waste gases are forced through the sodalime material 52, which, as explained above, substantially eliminatesthe carbon dioxide therefrom. The remaining, substantially carbondioxide free gas is brought into the base portion 14 of canister 12where it is mixed with an additional volume of the anestheticoxygenmixture, for recirculation into the lungs of the animal. Upon subsequentinhalation by the animal, more of the waste gases are drawn through thecarbon dioxide absorbing material into the base portion of canister 12where the process begins once again. As the animal continues to breathe,the reservoir bag 23, which initially was filled with oxygen, begins toaccumulate an anesthetic mixture. As will be explained below,periodically during the process the bag should be removed, emptied andrefilled with oxygen.

While the system is a closed one and leak-proof due to the one-piecemolded construction of canister 12 and the gas-tight slip-on connectionsof the hoses, and the like, a portion of the gas is neverthelessdepleted. This is due partially to the use of the exhaust valve 116 aswell as the use by the animal of a portion of the oxygen-anestheticcontent; thus oxygen must be added to the system regularly. For thesafest results it is best to slowly induce anesthesia during a five toten minute period. This is accomplished by adjusting the oxygen flowrate during the time the anesthetic is being induced into the animal;for example, for an animal such as a horse, the flow rate should be setat approximately four litres per minute or more. The vaporizer which inessence can be turned on and off by means of valve 74 should, for thesafest use of the anesthetic, be turned on fully for fifteen to thirtyseconds every minute or so until the animal reaches light surgicalanesthesia. It has been found that intermittent vaporization ofhalothane, or the like, is safer than continuous vaporization, since itis less likely that the animal will drift into a very deep place inanesthesia. The signs of light surgical anesthesia are a weak blinkingofthe eyelid, deep, even respiration occurring at a rate of five to twelveper minute, a steady flow pulse and mucous membranes red in color.

In order to assure denitrogenation and the prevention of hypoxia, it isadvisable to empty the reservoir bag which as mentioned above nowcontains an anesthetic mixture, and refill it by using the flood valve74 only with oxygen. If during the anesthetic process respirationbecomes shallow or jerky, the reservoir bag should likewise be removed,emptied, and refitted to neck portion 24 of aperture 18 in the baseportion 14, and be refilled with oxygen. in case the animal goes into astate of hypoxia, and respiration slows or stops, the reservoir bag,which is external to the canister 12 and therefore readily available,may be manually compressed to provide a forced breathing of oxygen forthe animal. This technique is known in the art as bagging.

The anesthetic should be kept as light as possible near the end of theanesthetizing period, especially immediately before the time arrives tobring the animal out of the anesthetic stupor. During this time,anesthetic gas and carbon dioxide should be washed out of the system asoften as possible. This can be accomplished by emptying the reservoirbag and refilling with oxygen four or five times at two or three minuteintervals. The endotracheal tube 106 should be removed as soon as theanimal begins to move about, coughs or swallows, after which the animalshould be taken to a recovery room.

The above description was given with the asssumption that a halothane,or the like, vaporizer unit, such as 58, would be used with the machinein the anesthetizing process. However, as also mentioned above, themachine according to the invention is adaptable to be used with thein-the-circuit vaporizer 59 when the utilization of low volatilemethoxyfluorane is required for faster induction and more controllableadministration of the anesthetic. In this case, the vaporizer jar 58would be bypassed by correctly positioning valve 74, so the oxygen willbe directed into base 14 of canister 12, and an in-the-circuit vaporizerunit 59 would be interconnected with hose 26 of the machine as shown inFlG. 1.

When unit 59 is used as the anesthetic source, oxygen from base M ispassed therefrom via hose 26 through inlet coupling 220 and intoaperture 211 thereof; the vane 229 being positioned as shown in dottedlines in FIG. 3. The oxygen passes into section 213 of jar 216 andthrough wick 212 which is saturated with the liquid methoxyfluorane injar 216. As the oxygen passes from section 213 of the jar through thewick and into section 2M thereof, a vapor of anesthetic gas is provided.The gas then passes out through opening 217 in plate 218, through outletcoupling 221, into hose 26 and on to the lungs of the animal. Theadministering of the methoxyfluorane is much the same as in the case ofhalothane; however, the methoxylfuorane produces a faster response fromthe animal, and one which is more controllable. As the animal breathesthe anesthetic vapor into his lungs and exhales the waste gases, vaporwill begin to accumulate in the reservoir bag 28 of the system and, theanimal may, as in the case of halothane, begin to receive too great anamount of anesthetic. If this occurs, the indicator bar 230 of vaporizerunit 59 may be turned so that vane 229 is positioned as shown in solidlines in FIG. 3, so as to bypass openings 211 and 217, and pass pureoxygen through channel 228 into outlet coupling 221 and on to the animalthrough hose 26.

If it becomes necessary to bag the animal, this can also be accomplishedby moving the vane 229 into the last mentioned position, and proceedingwith the bagging process as described above.

Thus, through the use of the anesthesia machine as described above,safe, efficient anesthetizing of animals, large ones in particular, maybe accomplished, and further, because of the novel, easy to assembleconstruction of the machine, it is reliable, leak-proof and convenientto handle.

It will be obvious to those skilled in the art that changes andmodifications may be made without departing from this invention in itsbroadest aspects, and

therefore the aim in the appended claims is to cover all such changesand modifications as come within the true spirit and scope of theinvention.

1 claim:

1. Animal anesthetizing apparatus comprising: canister means includingan inlet port and an outlet port, means within said canister forreceiving carbon dioxide absorbing material positioned intermediate saidports such that the exhaled waste gases from the animal will passthrough said material to purge said gases of carbon dioxide and a mixingchamber where said waste gases are mixed with oxygen; bi-directionalvalve means associated with said ports such that the gases being inhaledand exhaled by the animal can pass through said canister in only onedirection, thus defining a closed system having an inhalation portionand an exhalation portion within said canister; oxygen supply meanscommunicating with said mixing chamber for introducing oxygen into saidcanister; vaporizer means for providing anesthetic to said system, saidvaporizer means including first and second vaporizer units, said firstunit being perably connected with said oxygen supply means intermediatesaid supply means and said mixing chamber, said second unit beingoperably associated with the inhalation portion of said system andcomprising a jar member adapted to contain therein a quantity of liquidanesthetic, a wick positioned in said jar dividing it into two sections,a plate to which said wick is attached, said plate having a pair ofapertures therein, each of said apertures communicating with arespective section of said jar and with a compartment separated fromsaid jar by said plate and having inlet and outlet means provided inoperable connection with said system and control means for saidapparatus including valve means associated with said oxygen supply meansand providing an alternate path of communication with said canisterwhereby the oxygen being supplied will bypass said first unit and enterdirectly into said mixing chamber where it will be mixed with the wastegases, and additional control means for selectively connecting anddisconnecting said second unit to the system, said additional controlmeans including a vane movably mounted within said compartment betweensaid inlet and outlet means, said vane being positionable from a firstposition in blocking relation to said apertures so that gases may flowdirectly from said inlet means to said outlet means through saidcompartment, into asecond position where said vane blocks the directcommunication between said inlet and outlet means, whereby gasesentering said compartment through said inlet means will be channeledinto said jar prior to their passage out of said compartment by way ofsaid outlet means whereby when operably connected thereto purged wastegases and anesthetic free oxygen combined in said mixing chamber canthen be introduced into said second unit prior to inhalation by theanimal; and reservoir means attached to said canister in connection withsaid chamber.

2. Animal anesthetizing apparatus, said apparatus comprising: canistermeans including an inlet port and an outlet port, and means within saidcanister for receiving carbon dioxide absorbing material so that saidmaterial will be positioned intermediate said ports such that theexhaled waste gases from the animal will pass through said material topurge said gases of carbon dioxide and a chamber defined by saidcanister wherein exhaled waste gases are mixed with oxygen;bidirectional valve means associated with said ports such that the gasesbeing inhaled and exhaled by the animal can pass through said canisterin only one direction, thus defining a closed system having aninhalation portion and an exhalation portion communication therebetweenbeing established through said canister; oxygen supply meanscommunicating with said chamber for introducing oxygen into saidcanister; vaporizing means for adding anesthetic to said closed system,said vaporizing means including a jar member adapted to contain thereina quantity of liquid anesthetic, a wick positioned in said jar dividingit into two sections, a plate to which said wick is attached, said platehaving a pair of apertures therein, each of said apertures communicatingwith a respective section of said jar and with a compartment separatedfrom said jar by said plate and having inlet and outlet means providedin operable connection with said system, and a vane movably mountedwithin said compartment between said inlet and outlet means, said vanebeing positionable from a first position in blocking relation to saidapertures so that gases may flow directly from said inlet means to saidoutlet means through said compartment, into a second position where saidvane blocks the direct communication between said inlet and outletmeans, whereby gases entering said compartment through said inlet meanswill be channeled into said jar prior to their passage out of saidcompartment by way of said outlet means. and control means for saidapparatus including, valve means associated with said oxygen supplymeans and connecting same to said canister such that the oxygen beingintroduced into said system may be directed along one or the other oftwo alternate paths, one said path passing said oxygen through thevaporizer means prior to entry into said canister, and the other pathpermitting the oxygen to bypass the vaporizer means initially and bemixed with the purged waste gases in the canister with the resultinggaseous mixture then being subject to said vaporizer means.

1. Animal anesthetizing apparatus comprising: canister means includingan inlet port and an outlet port, means within said canister forreceiving carbon dioxide absorbing material positioned intermediate saidports such that the exhaled waste gases from the animal will passthrough said material to purge said gases of carbon dioxide and a mixingchamber where said waste gases are mixed with oxygen; bi-directionalvalve means associated with said ports such that the gases being inhaledand exhaled by the animal can pass through said canister in only onedirection, thus defining a closed system having an inhalation portionand an exhalation portion within said canister; oxygen supply meanscommunicating with said mixing chamber for introducing oxygen into saidcanister; vaporizer means for providing anesthetic to said system, saidvaporizer means including first and second vaPorizer units, said firstunit being operably connected with said oxygen supply means intermediatesaid supply means and said mixing chamber, said second unit beingoperably associated with the inhalation portion of said system andcomprising a jar member adapted to contain therein a quantity of liquidanesthetic, a wick positioned in said jar dividing it into two sections,a plate to which said wick is attached, said plate having a pair ofapertures therein, each of said apertures communicating with arespective section of said jar and with a compartment separated fromsaid jar by said plate and having inlet and outlet means provided inoperable connection with said system and control means for saidapparatus including valve means associated with said oxygen supply meansand providing an alternate path of communication with said canisterwhereby the oxygen being supplied will bypass said first unit and enterdirectly into said mixing chamber where it will be mixed with the wastegases, and additional control means for selectively connecting anddisconnecting said second unit to the system, said additional controlmeans including a vane movably mounted within said compartment betweensaid inlet and outlet means, said vane being positionable from a firstposition in blocking relation to said apertures so that gases may flowdirectly from said inlet means to said outlet means through saidcompartment, into a second position where said vane blocks the directcommunication between said inlet and outlet means, whereby gasesentering said compartment through said inlet means will be channeledinto said jar prior to their passage out of said compartment by way ofsaid outlet means whereby when operably connected thereto purged wastegases and anesthetic free oxygen combined in said mixing chamber canthen be introduced into said second unit prior to inhalation by theanimal; and reservoir means attached to said canister in connection withsaid chamber.
 2. Animal anesthetizing apparatus, said apparatuscomprising: canister means including an inlet port and an outlet port,and means within said canister for receiving carbon dioxide absorbingmaterial so that said material will be positioned intermediate saidports such that the exhaled waste gases from the animal will passthrough said material to purge said gases of carbon dioxide and achamber defined by said canister wherein exhaled waste gases are mixedwith oxygen; bi-directional valve means associated with said ports suchthat the gases being inhaled and exhaled by the animal can pass throughsaid canister in only one direction, thus defining a closed systemhaving an inhalation portion and an exhalation portion communicationtherebetween being established through said canister; oxygen supplymeans communicating with said chamber for introducing oxygen into saidcanister; vaporizing means for adding anesthetic to said closed system,said vaporizing means including a jar member adapted to contain thereina quantity of liquid anesthetic, a wick positioned in said jar dividingit into two sections, a plate to which said wick is attached, said platehaving a pair of apertures therein, each of said apertures communicatingwith a respective section of said jar and with a compartment separatedfrom said jar by said plate and having inlet and outlet means providedin operable connection with said system, and a vane movably mountedwithin said compartment between said inlet and outlet means, said vanebeing positionable from a first position in blocking relation to saidapertures so that gases may flow directly from said inlet means to saidoutlet means through said compartment, into a second position where saidvane blocks the direct communication between said inlet and outletmeans, whereby gases entering said compartment through said inlet meanswill be channeled into said jar prior to their passage out of saidcompartment by way of said outlet means. and control means for saidapparatus including, valve means associated with said oxygen supplymeans and connecting same to said canister such that the oxygen beingintroduced into said system may be directed along one or the other oftwo alternate paths, one said path passing said oxygen through thevaporizer means prior to entry into said canister, and the other pathpermitting the oxygen to bypass the vaporizer means initially and bemixed with the purged waste gases in the canister with the resultinggaseous mixture then being subject to said vaporizer means.